Local Wireless Network systems such as Institute of Electrical and Electronics Engineers (IEEE) 802.11 may operate in a predefined spectrum, such as, for example, a contiguous spectrum channel. In addition, the spectrum allowed for cellular licensed devices and devices operating in unlicensed bands such as industrial, scientific and medical (ISM), may not change over time.
In the United States, 408 MHz of spectrum from 54 MHz to 806 MHz may be allocated for television (TV). A portion of that spectrum may be redeveloped for commercial operations through auctions and for public safety applications. The remaining portion of the spectrum may remain dedicated for over-the-air TV operations. However, throughout the United States, portions of that spectrum resource may remain unused. The amount and exact frequency of unused spectrum may vary from location to location. These unused portions of spectrum may be referred to as TV White Space (TVWS). Because there are fewer TV stations located outside top metropolitan areas, most of the unoccupied TVWS spectrum is available in low population density or rural areas that tend to be underserved with other broadband options such as Digital Subscriber Line (DSL) or cable.
Each available TV channel may provide 6 MHz of spectrum capacity that may be used for broadband connectivity. TVWS may have large coverage areas due to long range propagation of signals at these frequencies. For example, a wireless local area network (WLAN) access point (AP) location operating in TVWS may provide coverage for an area of a few square miles. In contrast, wireless equipment such as IEEE 802.11b/g/n may have an average coverage area of 150 square feet.
Aggregating multiple channels and using a primary channel was introduced in IEEE 802.11n and 802.11ac. 802.11n and 802.11ac to deal with continuous channels. When operating in TVWS, multiple continuous channels may not be available, and aggregation on non-continuous channels may be required. The concept of silent measurement periods was introduced in IEEE 802.11 for detection of radar in the 5 GHz bands. A silent period may be used in physical layer/medium access control layer (PHY/MAC) devices operating in TVWS. In both cases, these were based on sensing silent period information on the beacon. However, they do not address sensing silent period information over aggregated channels.
The sse of silent periods may lead to a loss of throughput and an increase of delay/jitter. When a set of stations are silenced for measurements, the outgoing traffic may be buffered during the silent period, resulting in an increase of buffer space requirements. In addition, the loss of throughput and introduction of delay/jitter could adversely affect certain applications which are being run on the network.